One-piece channel shaped piston ring

ABSTRACT

A piston ring has an electrolytic Cr plating applied to the surface of the channel shaped steel article prior to slitting by the grinder to form a plurality of lateral slits.

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States Patent [1 1 Sugahara ONE-PIECE CHANNEL SHAPED PISTON RING [76] Inventor: Eisuke Sugahara, c/o 12-203 No. 1,

Akaban'edail-chorne, Tokyo, Japan [22] Filed: Nov. 11, 1971 211 Appl. No.: 197,745

Related US. Application Data [62] Division of Ser. No. 85,042, Oct. 29, 1970, Pat. No.

52 u.s.cl 277/201, 277/235A [51] Int. Cl Jugs 9 [58] Field ofSearch ..29/l56.6,156.2,156.3;

[ 6] References Cited- UNITED STATES PATENTS 1,635,530 7 1927 Broderick 277 235 A 2,380,654

7/1945 Lane et al'.,. 277/235 A Mar. 5, 1974 Primary ExaminerHerbertF; Ross Assistant Examiner-Robert 1. Smith Attorney, Agent, or FirmSughrue, Rothwell, Mion, Zinn & Macpeak 5 7 ABSTRACT A piston ring has an electrolytic Cr plating applied to the surface of the channel shaped steel article prior to slitting by the grinder to form a plurality of lateral slits.

2 Claims, 12 Drawing Figures air/95.403

PATENTED-MR 5m SHEET 2 OF 2 ONE-PIECE CHANNEL SHAPED PISTON RING This is a division of application Ser. No. 85,042, filed Oct. 29, I970 and now U.S. Pat. No. 3,729,790.

BACKGROUND OF THE INVENTION 2,932,543 and U. S. Pat. No. Re. 24,930, is produced by bending a channel shaped soft steel article having a plurality of lateral slits into a ring, so that the slits emerge on a pair of sliding faces of the ring. These slits often cause an end effect while subjected to the electrolyzing treatment, the electrolytic Cr plating being scarcely applied to the sliding faces. Therefore, hard and durable sliding faces have not been obtained for such channel shapedpistonring.

SUMMARY OF THE INVENTION This invention provides a novel method of electrolytic Cr plating the sliding faces of one-piece channel shaped piston rings capable of imparting favorable wear resistance and durabilityto' the sliding faces thereof.

BRIEF DESCRIPTION OF THE DRAWINGS An example of this invention will be explained with reference to accompanied drawings, wherein:

FIG. I is a plan view of a steel tape to be formed into the conventional channel shapedpiston ring, having a plurality of oil windows and lateral slits.

FIG. 2 is a lateral cross section of the conventional channel shaped piston ring of FIG. 1 along the slit.

FIG. 3 shows a cross section of an assembly composed of a piston a cylinder and the channel shaped piston ring of FIG. 1 inserted'therebetween.

FIG. 4 shows a plan view of a steel tape to be formed into a channel shaped piston ring according to this invention, having a plurality of oil windows.

FIG. 5 is a lateral cross section of the channel shaped steel sheet after bending.

FIG. 6 is a partly cross sectioned side view of a drum on which the channel shaped steel tape is'wound spirally to have the diameter equal to that of the final piston ring.

FIG. 7 is a lateral cross section of the final channel shaped piston ring along a slit.

FIG. 8 is a plan view of another steel tape to be formed into the channel shaped piston ring, having a plurality of laterally offset oil windows.

FIG. 9 is a lateral cross section of the final channel shaped piston ring produced by bending the steel tape of FIG. 8 into channel shape and further into a ring.

FIG. 10 is a schematic view of a grinder assembly having a plurality of heads to be applied to the channel shaped steel tape to form a plurality of the slits simultaneously.

FIG. II is a lateral cross section of the channel shaped piston ring combined with a corrugated expander, and

FIG. 12 is lateral cross section of a channel shaped piston ringcombined with a coil expander.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 3, the conventional channel shaped piston ring and the method of producing the latter will be first described. The steel sheet tape 1 having a plurality of rectangular oil windows 2 at regular intervals and lateral slits 3, 3 arranged alternately at respective sides of the tape, is bent longitudinally along line a-a to form a channel composed of a pair of sidewalls 4 and 5 and a bottom face including the oil windows 2.

End faces 6 and 6'-of both said walls serve as the sliding faces. This channel shaped article is cut into the desired length and bent into a ring. The thus obtained piston ring is inserted into an oil ring groove G of a piston so that the upper face 4' and the lower face 5 touch the groove walls, and the sliding faces 6 and 6 are brought into contact with a wall of a cylinder G which engages the piston. Thus, the excess oil stuck to the cylinder wall is scraped by the oil ring and drained through the oil windows 2 and oil ducts O in the piston to an oil pan (not shown), FIG. 3.

On the other'hand, a channel shaped piston ring according to this invention will be described referring to FIGS. 4 12. This channel shaped piston ring has the sliding faces plated with a hard and wear resistant Cr layer, which is not applied to the conventional piston ring, as-shown in FIGS. 1 3.

A thin steel sheet tape 1 having a plurality of rectangular oil windows 2 arranged at regular intervals along a longitudinal centerline X as shown in FIG. 4 is bent along a pair of longitudinal lines aa and a-u to form a channel shaped article 7 having sidewalls 4 and 5, as shown in FIG. 5. Then the steel articles 7 are wound spirally on a drum 8 having the outer diameter equal to the groove diameter D of the piston ring, shown in -ing part 9, as shown in FIG. 9. Finally, the channel shaped article 7 is cut into the desired length and formed into the ring shape.

In the aforesaid Cr plating step, since the channel shaped article 7 wound on the drum has no slits on the widewalls 4,5,during plating the end effect" cannot occur and a favorable Cr-plated layer is achieved.

In the aforesaid slit cutting step, since the same figured and sized oil windows are arranged along the centerline XX of the steel sheet tape 1, the slits 3 and 3' are easily and simultaneously cut in respective sidewalls 4 and 5 by a grinder to have the equal depths and to leave the connecting parts 9 In another example using a steel sheet tape I of FIG. 8 having oil windows 2 standing on different levels in every other window, if equal depth of the slits are cut simultaneously in both sidewalls 4, 5 by the grinder, one of the slits reaches the oil window 2 but the other does not reach to the latter and a connecting part 9 remains, as shown in the FIG. 9. The connecting parts 9 are formed alternately at every other window so as not to sever the channel shaped piston ring, and both slits can be formed in one step.

The cutting of the slits can be achieved by using one grinder head 10 several times in a plurality of cutting steps, but it is more advantageous to apply a multiple head grinder assembly on the wound article for multiple groove slitting in one step, as shown in FIG. 10.

The step of cutting the channel shaped wound article into a plurality of segments having the desired length may be included between the step of winding the channel shaped steel article on the drum and the step of electrolytic Cr plating.

As particularly mentioned above, since the electrolytic Cr plating which is hitherto impossible to apply, can be applied to the sliding faces 6, 6, which are brought into contact with the inner cylinder wall of the oil ring according to the method of this invention, the wear resistance of the oil ring is greatly increased. Moreover, since the many slits 3, 3, can be formed on both sidewalls of the oil ring, both the fit of the sliding faces to the inner cylinder wall and oil scratching effect are improved to-a great extent. In addition, a combination of this oil ring with a coiled expander 11 ofa corrugated expander 12 brings about advantageous results, FIGS. 11 and 12.

While this invention has been described with reference to particular embodiments thereof, it will be understood that the numerous modifications may be made by those skilled in the art without actually departing from the scope of this invention.

Therefore, the appended claims are intended to cover all such equivalent variations as coming within the true spirit and scope of the invention.

What is claimed is:

l. A one-piece channel shaped piston ring comprisa pair of same sized sidewalls with a bottom plate extending therebetween, said bottom plate having a plurality of oil windows therein,

an electrolytic Cr plating on the surfaces of said side plates, and at least covering the sliding end faces thereof, and

said sidewalls each having a plurality of longitudinally spaced, lateral slits therein, from said end face inwardly and formed therein subsequent to Cr plating thereof.

2. A one-piece channel shaped piston ring formed from a steel sheet tape, said ring comprising:

a pair of same sized side walls and a bottom plate extending therebetween, said bottom plate having a plurality of same sized oil windows arranged at zones alternately deviating from the centerline of the steel sheet tape in laterally offset manner, said side walls each having a plurality of longitudinally spaced, lateral slits therein from said end face in wardly in aligned fashion, such that the slit reaches the oil window edge at one sidewall but the opposite sidewall slit is spaced from that oil window to leave a connecting part between that slit and the oil window, and an electrolytic Cr plating carried by the surface of the walls and at least covering the I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 9 .3 D t d March 5, 1974 I v I Eisuke Sugahara It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In The Heedifig:

The Claim To Priority Was Omitted. Should be.

"-' 0-00.00 oaooooouoooouoou Signed and sealed this 9th day of July 197 (SEAL) Attest:

C. MARSHALL DANN McCOY M.GIBSO N,J'R. Attesting Officer Commissioner of Patents USCOMM-DC 60376-P69 FORM PQ-HJSO (10-69) r us. GOVERNMENT PRINTING omc: 194s o-ase-au. 

1. A one-piece channel shaped piston ring comprising: a pair of same sized sidewalls with a bottom plate extending therebetween, said bottom plate having a plurality of oil windows therein, an electrolytic Cr plating on the surfaces of said side plates, and at least covering the sliding end faces thereof, and said sidewalls each having a plurality of longitudinally spaced, lateral slits therein, from said end face inwardly and formed therein subsequent to Cr plating thereof.
 2. A one-piece channel shaped piston ring formed from a steel sheet tape, said ring comprising: a pair of same sized side walls and a bottom plate extending therebetween, said bottom plate having a plurality of same sized oil windows arranged at zones alternately deviating from the centerline of the steel sheet tape in laterally offset manner, said side walls each having a plurality of longitudinally spaced, lateral slits therein from said end face inwardly in aligned fashion, such that the slit reaches the oil window edge at one sidewall but the opposite sidewall slit is spaced from that oil window to leave a connecting part between that slit and the oil window, and an electrolytic Cr plating carried by the surface of the walls and at least covering the sliding end faces thereof. 